Manufacture of pipe bends



Feb. 8, 192 v 1,511,277

A. SCHMIDT MANUFACTURE OF PIPEBENDS Original Filed ,April 10. 1924 Patented Feb. 8, 1927.

UNITED STATES I I -1 ,6 17,277. PATENT. OFFICE.

ALFRED scinma'r, or nussannonr, ennirm.

muracruan or rn-nnnnns.

Original application filed April 10, 1924, Serial No. 705.658; and in Germany June 6, 1923. Divided an d.

this application filed April 16, 1926. Serial No.102,585.

In steam piping, more particularly in the case of pipe lines for conveying superheated steam of high temperature, corrugated pipes are used for taking up the longitudinal expansion at the bends, 1S they give more readily than smooth bent steam piping. ocalled expansion loops madevof corrugated piping are also introduced into straight runs of piping. Such corrugated pipes are made by heating and cooling alternate zonesof the pipe, the pipe being compressed axially. In .order to eliminate the strains in the material due to the alternate heating and cooling, the finished pipe is finally annealed in the annealing furnace. The ordinary corrugated pipes have various disadvantages, owing to thefact that the corrugations pass right round them. Owing to their great surface, the heat radiation is relatively great and eddies are formed by the corrugations in the flow of steam, which may cause'considerable pressure losses when the velocity of the steam is great. The present invention which" of app a division 705,658, filed April 10, 1924, has-for its object to provide'a thick walled pipe capable of acting as an expansion loop which will be free from the drawbacks above referred to, and the invention consists in a method of bending thick-walled pipes by locally heat-ing'portions of the'wall of the; pipe which is to form the inner side of the bend and bending the pipe. By this means a ipe is produced having outwardly exten ing bulges in its wall located only on the inner side of the bend.

' In-the accompanying drawing,

Figure lshows aside view ofa-pi e bend, Figure 2 the same bend in section and Figure? an expansion loop. The-pipes according to the invention are made'jby filling 'a steam pi e (patent-welded, seamless or the like) wit sand and there- ,u on bending it in a colder. hot state, the p ace at which the crease is .to be formed "being specially heated b% means of a welding burner or the I like. wing to the pipe being filled with sand, the place thus heated 'will bulge outwards. In this manner one crease after another is formed, the first crease, .erably first formed and the intermediate creases subsequently these bends the 0 lie only along the s earn has the ten ency to slide along lience is at least as great" as in the case of licants co-pending application No.

the thirdcrease and so on being prefr pipe is no longer bent, but straight, there are no creases. Hence the radiationsurface 1s conszderably smaller than is the case in I corrugated pipes. One great advantage, is

that eddying in the flow of steam is very great! reduced.v Owin to centrifugal force the outer curve ointhe bend, which is smooth in pipes made according to the present invention. The material is less stressedin the process of manufacture. than is the case in I corrugated pipes, as there is no alternate heating and simultaneous cooling of adjacent zones and no axial compression of the material. Hence, the durability is greater than in the case .of corrugated pipes, while the cost of manufacture is less. The resilcorrugated pipes. The durability isgreater than is the case with smooth bends, as the wall of the bend is not extended at the outer periphery and is therefore not weakened, the material being compressed on the inner side of the bend "and taken. up by the creases.

WhatIclaim'is:-'--

1,. A method of 'bend' g thick-walled pipes. consisting in successively heating spaced portions of thepipes'on the side which is to form the insid'e'of the bend, and bending the pipe .by a small amount each time after a portion of the pip is heated, thereby causing the heated po ion to bulge outwardly.

2. A method of bending thick-walledpipes, consisting in filling the pipe with sand, successively heating spaced portions of the pipe on the side which is to form the inside of the be'nd, and bending the pipe by a-small amountfeach time after a portion of thepipe is heated, thereby causing the heated portion to bulge-outwardly. '3'. A method of bending thick-walled pipes, consisting in filling the pip; with sand, -locally heating portions of the j all of the ipe, which are to form alternate bulges on t 1e inner side of the bend, partially bending the pipe, heating the portions of the ipe 105 wall intermediate of the said alte ate bulges and completingthe bend, as set forth.

In testimony whereof I have signed my name to this specificatio y ALFRED SCHMIDT. 

